This is a rather common complaint among some persons experiencing palpitations. It is described as a sensation that travels deep within the arm and produces a mild electrical shock sensation or even pain. It is often seen in cases where GI problems are also present such as indigestion or bloating. The nerve plexus which supplies innervation of the arm is prone to stimulation just as any other nerve, the consequence of which is the sensation of electricity or pain, even a tense or tight feeling. It is, nevertheless, mere stimulation.

It's important not to confuse this type of event with the sort of referred pain observed in some patients experiencing an ischemic episode or the heart and proximal vascular complex. Realize that pain of this type is on the order of magnitude far greater in intensity and duration that what you've been experiencing with regard to your palpitations. The pain associated with tissues being deprived of oxygen is quite substantial and typically prevails for periods greater than 20 minutes or so, most importantly accompanied by other symptoms relative to the ischemic event.

Changes in body position against the effects of gravity always carry the potential for palpitation events to occur. The primary reason is a shift in the organs and tissues within the abdomen and chest cavity that, while subtle to a certain degree, nevertheless are capable of inducing the vagus nerve to respond with an inappropriate evoked potential (electric signal).

These are all common observations by persons experiencing this type of palpitation.

You'll be just fine.

Best regards and Good Health

Thanks for the reply and sorry that you are suffering with the things also
Glen